Filling cavities



cowosmons, Cross Reference txam'ner COATING 0R PLASTIC Dec. 8, 1936. L 'A KA' ET AL 2,063,667

' FILLING cmfxnss Original Filed Feb. 7, 1933 Lad is lqus Far/(as and I 6 "Paul H ar-tetk l five/722: -M J-M M Attorney UNITED STATES PATENT OFFICE 2,063,667 FILLING cAvrrms Ladislaus Farkas and Paul Harteck, Berlin, Germany Application February 7, 1933, Serial No. 655,667.

Renewed July 28, 1936. In Germany February 13, 1932 Claims.

Our invention relates to the filling of cavities with a suitable mass. The hitherto known methods of filling or closing cavities, such as small fissures, cracks, slits, or ridges in any kind of 5 material, with a solid substance, consist in introducing into the cavity a substance in liqui state and causing said liquid to solidif e cavity. The introduction of the liquid substance 3 into the narrow cavity, however, presents con- 1 siderable difiicultiesyjheamor any other inert [9 gas, present in the avity, does not escape entirely, but forms bubbles in the liquid during its introduction and thereby prevents this latter from s completely filling the cavity. The difliculties are $1specially great when a cavity closed on one side is to be entirely filled.

These disadvantages are very seriously noticeable in dentistry. If for instance the root canals of the teeth are to be filled, it is especially important that the filling extends right to the apex of the root-canal and also completely fills the very fine lateral ramifications. In practice it was not possible hitherto to reliably fill cavities of the kind mentioned in all their parts because the air could not be entirely expelled by the filling substance and thus prevented this latter from completely penetrating into the canals.

We have found that the difiiculties described can be overcome by the new steps forming part of our invention. The air, or any other inert gas present in the cavity to be filled, is, in the first place,replacedbya gas adapted to react with the filling mass used, such as, for instance, carbon dioxide (CO2). If now a filling mass having an alkaline reaction is introduced into the cavity, e. g. a root-canal filled with carbon dioxide, it absorbs this gas and, thereby, is sucked into the canal and may penetrate right to the apex of the root and into the tiniest canals without any reslstance.

Our invention is not restricted to the use of carbon dioxide, it being possible, for instance, to use ammonia in connection with a neutral or acid filling mass adapted to absorb ammonia in a physical or chemical way, or a halogen or a hydrogen halogenide, or S02, the filling mass consisting of aqueous solutions or organic materials which are fit to absorb these gases With our improved method the filling mass must be liquid. If it is desired subsequently to have it solidified or in a paste-like consistency, a composition is used which is capable of solidifying in the cavity after some time.

We have found that in this case preferably a mixture is used which not only causes the gas and the main mass to react with one another, but leads to a further reaction which proceeds more slowly and which causes the filling to solidify.

Thus, a material may be added to the liquid filling mass which reacts with the solvent in a binding reaction. A part of the solvent is thereby directly absorbed and the combination between the added substance and the solvent may also result in the formation of reaction products, e. g. ions, which in turn act as precipitating agents. We add, for instance, gypsum to an aqueous solution having an alkaline reaction. The gypsum gradually absorbs water and forms ions which precipitate one of the dissolved materials so that, owing to cooperation of these factors, the mixture solidifies after a certain time. In most cases it is still more advisable to employ a substance which at the beginning is dissolved in the solution employed, e. g. a suitable acid anhydride or a lactone. As in these cases slow reactions arise, the mixture coagulates only after a certain time which can be varied at will by the choice of suitable components.

A slow reaction and solidification, the duration of which can be controlled to a great extent by properly choosing and mixing the components, also takes place when an ester is added to an alkaline filling mass. The ester is gradually saponified, thus partly neutralizing the solution, and causing salts to form and to precipitate in the solid state and giving rise to the precipitation or coagulation of further dissolved substances. It has, for instance, been found advisable to use as a filling mass a solution of water-glass in a solution of sodium hydroxide with an ester added.

Owing to the presence of the sodium hydroxide,

the filling mixture is sufiiciently thinly liquid even with a high percentage of water-glass. The chemical processes in this system are the following:The ester is gradually saponified by the caustic soda solution, thereby forming an alcohol and an acid. The acid neutralizes part of the caustic soda; the salt so formed together with the alcohol precipitates the water-glass, forming a silicious skeleton which fills the entire cavity.

It is a particular advantage of our process that m6. cowosmous, i

COATING R PLASTIC of two or more substances, or mixtures, which are kept separately and are mixed only shortly before being used. In order to obtain a thorough mixture, it is advisible to give to the single components a similar specific gravity.

If, in the above-mentioned composition, the specific gravity of the ester difiers from that of i the solution to which it is added, it may be mixed 20 mixed, be as small as possible, so that they can easily be worked into a fine emulsion which remains stable until the whole substance is solidified. This can be attained by adding an emulsifying agent; highly polymeric natural products,

25 or for instance ethyl cellulose, or gelatine are,

among others, suitable for this purpose.

We have found furthermore that the precipitate becomes particularly uniform if a carbohydrate, or a pclyvalent alcohol such as mannitol,

30 or glycerol, and also sugar is added to the solution.

We may use as a filling mass a thixotropic liquid. Such liquids solidify after an exactly determined time which, by additions to the liquid, can be controlled finely and in very broad limits.

It is, of course, possible to use several of the means described at the same time, e. g., add an ester and a lactone to a strongly alkaline solution of water-glass.

In dentistry, one of the ordinary disinfectants 40 may be added to the filling mass, e. g., chlorothymol or iodoform. As these substances are not soluble in water but highly soluble in organic solvents, it is advisable when using an ester to dissolve it in this latter and to add the solution ob- 45 tained to the filling substance.

In many cases, especially in dentistry, it is desirable that the finished filling be visible in the radiograph. For this purpose a compound of an element with a high atomic weight is added to 50 the filling mass. Thus, caesium hydroxide is used instead of or together with, the caustic soda, or an appropriate iodine compound, such as an iodide, is added.

Examples (1) Commercial sodium water-glass has potassium hydroxide added until the solution is 0.25 normal and with so much NaCl that precipitation of silicic acid is just avoided; shortly be- 00 fore using, finely pulverized half overburnt gypsum is stirred into this solution. The mixture is sucked into the cavity by the carbon dioxide and solidifies there, after the gypsum has been hydrated.

65 (2) 100 cc. of a commercial solution of waterglass, having a specific weight of 1.33, are diluted with 65-70 cc. of water, and 50 g. of mannitol and 5-8 g. of solid caustic soda are dissolved therein; besides, 70 g. or a mixture of K1 and 70 CsI may be added. Before use, 1 part of a second mbn is added to 8 parts of this solution, this second solution having about the same specific weight and consisting of methyl acetate with several per cent of ethyl iodide or ethylene bro- 76 mide.

Cross Reference (3) 6-8 g. KOH and 25 g. of a mixture of KI, RM and CsI are dissolved in '75 cc. of a commercial water-glass solution, and the solution is diluted with 15-20 cc. of glycerol. This solution is emulsified with almost the same quan- 5 tity, but not more, of a mixture of 30 volume parts of ethyl acetate, '70 volume parts of iodated benzenes or bromoform and 1-3 parts of ethyl cellulose and gelatine.

(4) 100 cc. of water-glass solution, having a 10 specific weight of 1.33, are mixed with 30 cc. of glycerol, and 35 g. of a mixture of about equal parts of KI, RbI, CsI are dissolved therein. 5 parts of this solution are mixed-prior to use with 1 part of a second solution, which consists of salicylic or benzoic methyl ester, ethyl acetate and diiodobenzene. To the second mixture small quantities of purest gutta-percha can be added as an emulsifying agent and about 3% of chlorothylmol as a disinfectant.

(5) 30 volume parts of a saturated aqueous solution of bismuth-nitrate and mannitol are mixed with 70 volume parts of a water-glass solution, which is normal with respect to KOH; to this solution some per cent by weight of an alkali iodide may be added. Prior to use, 15 volume parts of a mixture of methyl and ethyl acetates are added to this solution.

Filling masses of the kind described are sucked into the cavity by the carbon dioxide on acmount of their alkaline reaction; owing to their contents in elements of high atomic weight, the finished fillings are visible in the radiograph.

When carrying out the process, it must be taken into consideration that the cavity to be filled, e. g., the tooth-root canal, must be filled with the gas and does not contain any air, or any other inert gas, when the filling substance is introduced.

For the performance of our new process a special device can be used. This device consists substantially of a double canula the one tubule of which projects over the other, and to which, at a proper distance from the end, a rubberplate, or the like, can be fixed, which during the process is placed on the edge of the cavity, e. g. of the tooth. The gas is introduced through the shorter tubule of the canula, and then the filling mass through the longer projecting tubule. So a quiet afllux of the filling mass is obtained, and this latter will not be ejaculated again from the cavity, e. g., the root-canal, by the gas in a stage in which the gas is still flowing and the filling mass has already been allowed to enter the cavity. The rubber-plate elastically covers the cavity and makes it difilcult for air to enter the root-canal during the filling operation.

In the accompanying drawing the use of our improved device is shown by way of example, the double canula serving for filling a tooth-root canal according to our improved process.

According to Fig. l, the root-canal w of the drilled tooth, the nerve of which has been killed and removed, is filled with the aid of the device. Through the tubule a carbon dioxide is allowed to enter for about 1 minute, and then a filling mass of an alkaline reaction is let in through the tubule b. The rubber-plate is designated by the letter 0.

Fig. 2 shows the same double canula in crosssection.

In Fig. 3 a double canula is shown in which the one tubule is not fixed into the other, but the two tubules a. and b are arranged one beside the other. It is, or course, also possible to com- Examine:

pose the canula of more than two tubules. In this case the gas tubules must be shorter than those through which the liquid is introduced.

For the purpose of treating teeth the canula has preferably a circular cross-section. Otherwise, its cross-section will be adapted to the form of the cavityto be filled.

For dental purposes the canula may consist of non-corrodible steel or nickel, or, if desired, platinum. The canula described can be arranged in such a manner that it may be fastened to one of the usual carbon dioxide cylinders. In connection therewith a tap is used which permits cutting of! the flow of carbon dioxide as soon as, or immediately after the filling mass begins to be introduced.

We claim:

1. A process for filling tooth cavities, comprising the steps of replacing any inert gas contained in the tooth cavity by a gas adapted to be absorbed by the tooth filling mass and then introducing the tooth filling mass.

2. A process for filling tooth cavities, comprising the steps of replacing any inert gas contained in the tooth cavity by a gas adapted to be physically absorbed by the tooth filling mass, and then introducing the tooth filling mass.

3. A process for filling tooth cavities, comprising the steps of replacing any inert gas contained in the tooth cavity by a gas adapted to be chemically absorbed by the tooth filling mass, and then introducing the tooth filling mass.

4. A process for filling tooth cavities, comprising the steps of replacing any inert gas contained in the tooth cavity by carbon dioxide, and then introducing a tooth filling mass having an alkaline reaction.

5. A process for filling tooth cavities, comprising the steps of replacing any inert gas contained in the tooth cavity by a gas adapted to be absorbed by the tooth filling mass, and then introducing a filling mass adapted to solidify in the cavity.

LADISLAUS FARKAS. PAUL HARTECK. 

